This invention relates to a transfer-type flat electromagnetic relay.
As will later be described more in detail with reference to one of nearly ten figures of the accompanying drawing, a transfer-type electromagnetic relay disclosed in Japanese Pre-patent Publication or Published Unexamined Patent Application No. Syo 53-68851 or 68851/78 comprises a housing having a first and a second end, a first and a second lead fixed to the housing adjacent to the first and the second ends, a lead pair fixed to the housing centrally between the first and the second ends with a predetermined spacing, a first and a second fixed contact stud attached to the first and the second leads, and a first and a second movable contact stud attached to both end portions of a leaf spring. A central portion of the leaf spring is welded to the lead pair so that the first and the second movable contact studs may serve as a first and a second contact in cooperation with the first and the second fixed contact studs.
A rectangular permanent magnet having a length shorter than the leaf spring, is placed on a coil wound around a flat core. An armature having a length shorter and longer than the leaf spring and the magnet and a width narrower than the predetermined spacing, is urged by the leaf spring to a hinge rod positioned transversely on the magnet for seesaw movement about an axis of the hinge rod. The core has extensions extended along end faces of the coil and longitudinal ends of the magnet near to both ends of the armature. The magnet has poles of the same name adjacent to the longitudinal ends and a common pole of the different name at the center.
When the coil is supplied with an electric current, a magnetic field appears to produce poles of names same as and different from the adjacent poles of the permanent magnet near the core extension ends. Due to a difference between attraction and repulsion given to the armature ends, one and the other of the first and the second contacts are closed and open depending on the sense of current flow. The permanent magnet is also for keeping closure of the contact even after disappearance of the magnetic field until the current is caused to flow through the coil in the reversed sense.
Because of a stack of the armature, the permanent magnet, and the coil, the relay is considerably thick. On driving the relay, an appreciable amount of the electric power is consumed because a sufficiently strong pole must be produced adjacent to the differently named pole of the permanent magnet although the other pole of the permanent magnet may augment repulsion given to the other armature end by the pole produced with the same name near the other core extension end.